-
International Journal of Molecular... Sep 2020Transthyretin (TTR) is a homotetrameric protein involved in human amyloidosis, including familial amyloid polyneuropathy (FAP). Discovering small-molecule stabilizers of...
Transthyretin (TTR) is a homotetrameric protein involved in human amyloidosis, including familial amyloid polyneuropathy (FAP). Discovering small-molecule stabilizers of the TTR tetramer is a therapeutic strategy for these diseases. Tafamidis, the only approved drug for FAP treatment, is not effective for all patients. Herein, we discovered that benzbromarone (BBM), a uricosuric drug, is an effective TTR stabilizer and inhibitor against TTR amyloid fibril formation. BBM rendered TTR more resistant to urea denaturation, similarly to iododiflunisal (IDIF), a very potent TTR stabilizer. BBM competes with thyroxine for binding in the TTR central channel, with an IC similar to IDIF and tafamidis. Results obtained by isothermal titration calorimetry (ITC) demonstrated that BBM binds TTR with an affinity similar to IDIF, tolcapone and tafamidis, confirming BBM as a potent binder of TTR. The crystal structure of the BBM-TTR complex shows two molecules binding deeply in the thyroxine binding channel, forming strong intermonomer hydrogen bonds and increasing the stability of the TTR tetramer. Finally, kinetic analysis of the ability of BBM to inhibit TTR fibrillogenesis at acidic pH and comparison with other stabilizers revealed that benzbromarone is a potent inhibitor of TTR amyloidogenesis, adding a new interesting scaffold for drug design of TTR stabilizers.
Topics: Amyloid; Benzbromarone; Benzoxazoles; Binding Sites; Binding, Competitive; Crystallography, X-Ray; Diflunisal; Drug Repositioning; Gene Expression; Humans; Hydrogen Bonding; Kinetics; Molecular Docking Simulation; Neuroprotective Agents; Prealbumin; Protein Binding; Protein Conformation, alpha-Helical; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Protein Multimerization; Protein Stability; Recombinant Proteins; Thermodynamics; Thyroxine; Tolcapone
PubMed: 32998442
DOI: 10.3390/ijms21197166 -
Journal of the American Heart... Oct 2020Background The emergence of specific therapies for transthyretin cardiac amyloidosis (CA) warrants the need for a systematic review of the literature. Methods and...
Background The emergence of specific therapies for transthyretin cardiac amyloidosis (CA) warrants the need for a systematic review of the literature. Methods and Results A systematic review of the literature was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A systematic search was performed on MEDLINE, PubMed, and Embase databases on November 29, 2019. Studies were selected based on the following predefined eligibility criteria: English-language randomized controlled trials (RCTs), non-RCTs, or observational studies, which included adult patients with variant/wild-type transthyretin-CA, assessed specific therapies for transthyretin-CA, and reported cardiovascular outcomes. Relevant data were extracted to a predefined template. Quality assessment was based on National Institute for Health and Care Excellence recommendations (RCTs) or a checklist by Downs and Black (non-RCTs). From 1203 records, 24 publications were selected, describing 4 RCTs (6 publications) and 16 non-RCTs (18 publications). Tafamidis was shown to significantly improve all-cause mortality and cardiovascular hospitalizations and reduce worsening in 6-minute walk test, Kansas City Cardiomyopathy Questionnaire-Overall Summary score, and NT-proBNP (N-terminal pro-B-type natriuretic peptide) in variant/wild-type transthyretin-CA. Patisiran showed promising results in a subgroup analysis of patients with variant transthyretin-CA, which have to be confirmed in RCTs. Inotersen showed conflicting results on cardiac imaging parameters. The one study on AG10 had only a 1-month duration and cardiovascular end points were exploratory and limited to cardiac biomarkers. Limited evidence from noncomparative single-arm small non-RCTs existed for diflunisal, epigallocatechin-3-gallate (green tea extract), and doxycycline+tauroursodeoxycholic acid/ursodeoxycholic acid. Conclusions This systematic review of the literature supports the use of tafamidis in wild-type and variant transthyretin-CA. Novel therapeutic targets including transthyretin gene silencers are currently under investigation.
Topics: Amyloid Neuropathies, Familial; Benzoxazoles; Cardiomyopathies; Cardiovascular Agents; Genetic Therapy; Humans
PubMed: 32969287
DOI: 10.1161/JAHA.120.016614 -
Neurology and Therapy Dec 2020ATTR amyloidosis is caused by systemic deposition of transthyretin (TTR) and comprises ATTRwt (wt for wild-type) amyloidosis, ATTRv (v for variant) amyloidosis, and... (Review)
Review
ATTR amyloidosis is caused by systemic deposition of transthyretin (TTR) and comprises ATTRwt (wt for wild-type) amyloidosis, ATTRv (v for variant) amyloidosis, and acquired ATTR amyloidosis after domino liver transplantation. ATTRwt amyloidosis has classically been regarded as cardiomyopathy found in the elderly, whereas carpal tunnel syndrome has also become a major initial manifestation. The phenotypes of ATTRv amyloidosis are diverse and include neuropathy, cardiomyopathy, and oculoleptomeningeal involvement as the predominant features, depending on the mutation and age of onset. In addition to variant TTR, the deposition of wild-type TTR plays a significant role, even in patients with ATTRv amyloidosis. The formation of amyloid fibrils tends to occur in association with the basement membrane. The thickening or reduplication of the basement membrane surrounding endoneurial microvessels, which is similar to diabetic neuropathy, is observed in ATTRv amyloidosis, suggesting that common mechanisms, such as an accumulation of advanced glycation end products, may participate in the disease process. In addition to direct damage caused by amyloid fibrils, recent studies have suggested that the toxicity of nonfibrillar TTRs, such as TTR oligomers, participates in the process of tissue damage. Although liver transplantation has been performed for patients with ATTRv amyloidosis since 1990, late-onset patients were not eligible for this treatment. However, as the efficacy of orally administered tafamidis and diflunisal, which stabilize TTR tetramers, was suggested in the early 2010s, such late-onset patients have also become targets for disease-modifying therapies. Additionally, recent studies of small interfering RNA (patisiran) and antisense oligonucleotide (inotersen) therapies have demonstrated the efficacy of these gene-silencing agents. A strategy for monitoring patients that enables the choice of an appropriate treatment from comprehensive and long-term viewpoints should be established. As many patients with ATTR amyloidosis are aged and have heart failure, they are at increased risk of aggravation if they are infected by SARS-CoV2. The optimal interval of evaluation should also be considered, particularly in this COVID-19 era.
PubMed: 32948978
DOI: 10.1007/s40120-020-00210-7 -
Polymers Sep 2020Poly(2-(diethylamino)ethyl methacrylate-co-divinylbenzene) (poly(DEAEMA-co-DVB)) microspheres with mixed-mode weak anion-exchange (WAX) character were successfully...
Facile Synthesis of Mixed-Mode Weak Anion-Exchange Microspheres via One-Step Pickering Emulsion Polymerization for Efficient Simultaneous Extraction of Strongly and Weakly Acidic Drugs from Reservoir Water.
Poly(2-(diethylamino)ethyl methacrylate-co-divinylbenzene) (poly(DEAEMA-co-DVB)) microspheres with mixed-mode weak anion-exchange (WAX) character were successfully fabricated for the first time via facile one-step Pickering emulsion polymerization. The obtained poly(DEAEMA-co-DVB) particles had good spherical geometry, uniform particle size in the range of 30-40 µm, a large specific surface area of 575 m/g, and a pore size range of 5-30 nm, according to the SEM and nitrogen adsorption-desorption results. Using these mixed-mode WAX microspheres as packing material, a reliable and robust analytical method based on solid phase extraction and high performance liquid chromatography with ultraviolet detection (SPE-HPLC-UV) was developed for simultaneous determination of six strongly and weakly acidic nonsteroidal anti-inflammatory drugs (NSAIDs, niflumic acid, diflunisal, naproxen, ketoprofen, mefenamic acid, and diclofenac) in reservoir water. Under optimized conditions, it was applicable to preconcentrate up to 500 mL of reservoir water samples on the WAX cartridges with satisfying recoveries (88-96%) for all the NSAIDs tested. The limits of detection were in the range of 0.002-0.025 μg L, respectively. Our results showed that the developed mixed-mode WAX poly(DEAEMA-co-DVB) phase containing a tertiary amine with a pKa value of approximately 10.7 could be used for simultaneous clean-up and preconcentration of strongly and weakly acidic organic pollutants in real environmental water, which could not be achieved by single use of quaternary ammonium strong anion-exchange phase or weaker primary and secondary amine anion-exchange.
PubMed: 32937903
DOI: 10.3390/polym12092089 -
Molecules (Basel, Switzerland) Sep 2020Biomedicine represents one of the main study areas for dendrimers, which have proven to be valuable both in diagnostics and therapy, due to their capacity for improving... (Review)
Review
Biomedicine represents one of the main study areas for dendrimers, which have proven to be valuable both in diagnostics and therapy, due to their capacity for improving solubility, absorption, bioavailability and targeted distribution. Molecular cytotoxicity constitutes a limiting characteristic, especially for cationic and higher-generation dendrimers. Antineoplastic research of dendrimers has been widely developed, and several types of poly(amidoamine) and poly(propylene imine) dendrimer complexes with doxorubicin, paclitaxel, imatinib, sunitinib, cisplatin, melphalan and methotrexate have shown an improvement in comparison with the drug molecule alone. The anti-inflammatory therapy focused on dendrimer complexes of ibuprofen, indomethacin, piroxicam, ketoprofen and diflunisal. In the context of the development of antibiotic-resistant bacterial strains, dendrimer complexes of fluoroquinolones, macrolides, beta-lactamines and aminoglycosides have shown promising effects. Regarding antiviral therapy, studies have been performed to develop dendrimer conjugates with tenofovir, maraviroc, zidovudine, oseltamivir and acyclovir, among others. Furthermore, cardiovascular therapy has strongly addressed dendrimers. Employed in imaging diagnostics, dendrimers reduce the dosage required to obtain images, thus improving the efficiency of radioisotopes. Dendrimers are macromolecular structures with multiple advantages that can suffer modifications depending on the chemical nature of the drug that has to be transported. The results obtained so far encourage the pursuit of new studies.
Topics: Animals; Anti-Inflammatory Agents; Biomedical Technology; Cell Death; Dendrimers; Diagnostic Imaging; Humans; Toxicity Tests
PubMed: 32882920
DOI: 10.3390/molecules25173982 -
Blinded potency comparison of transthyretin kinetic stabilisers by subunit exchange in human plasma.Amyloid : the International Journal of... Mar 2021Transthyretin (TTR) tetramer dissociation is rate limiting for aggregation and subunit exchange. Slowing of TTR tetramer dissociation kinetic stabiliser binding slows...
Transthyretin (TTR) tetramer dissociation is rate limiting for aggregation and subunit exchange. Slowing of TTR tetramer dissociation kinetic stabiliser binding slows cardiomyopathy progression. Quadruplicate subunit exchange comparisons of the drug candidate AG10, and the drugs tolcapone, diflunisal, and tafamidis were carried out at 1, 5, 10, 20 and 30 µM concentrations in 4 distinct pooled wild type TTR (TTRwt) human plasma samples. These experiments reveal that the concentration dependence of the efficacy of each compound at inhibiting TTR dissociation was primarily determined by the ratio between the stabiliser's dissociation constants from TTR and albumin, which competes with TTR to bind kinetic stabilisers. The best stabilisers, tafamidis (80 mg QD), AG10 (800 mg BID), and tolcapone (3 x 100 mg over 12 h), exhibit very similar kinetic stabilisation at the plasma concentrations resulting from these doses. At a 10 µM plasma concentration, AG10 is slightly more potent as a kinetic stabiliser vs. tolcapone and tafamidis (which are similar), which are substantially more potent than diflunisal. Dissociation of TTR can be limited to 10% of its normal rate at concentrations of 5.7 µM AG10, 10.3 µM tolcapone, 12.0 µM tafamidis, and 188 µM diflunisal. The potency similarities revealed by our study suggest that differences in safety, adsorption and metabolism, pharmacokinetics, and tissue distribution become important for kinetic stabiliser clinical use decisions.
Topics: Amyloid; Amyloid Neuropathies, Familial; Benzoates; Benzoxazoles; Cardiomyopathies; Diflunisal; Humans; Kinetics; Prealbumin; Protein Aggregates; Protein Binding; Protein Multimerization; Protein Subunits; Pyrazoles; Tolcapone
PubMed: 32811187
DOI: 10.1080/13506129.2020.1808783 -
Polymers Jul 2020The effects of three hydrophilic polymers, namely, carboxymethyl cellulose sodium (CMC-Na), polyvinyl alcohol (PVA) and poloxamer-188 (PXM-188) on the solubility and...
The effects of three hydrophilic polymers, namely, carboxymethyl cellulose sodium (CMC-Na), polyvinyl alcohol (PVA) and poloxamer-188 (PXM-188) on the solubility and dissolution of diflunisal (DIF) in complexation with β-cyclodextrin (βCD) or hydroxypropyl β-cyclodextrin (HPβCD), were investigated. The kneading method was used at different drug to cyclodextrin weight ratios. Increases in solubility and drug release were observed with the DIF/βCD and DIF/HPβCD complexes. The addition of hydrophilic polymers at 2.5, 5.0 and 10.0% w/w markedly improved the complexation and solubilizing efficiency of βCD and HPβCD. Fourier-transform infrared (FTIR) showed that DIF was successfully included into the cyclodextrin cavity. Differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) confirmed stronger drug amorphization and entrapment in the molecular cage of cyclodextrins. The addition of PVA, CMC-Na or PXM-188 reduced further the intensity of the DIF endothermic peak. Most of the sharp and intense peaks of DIF disappeared with the addition of hydrophilic polymers. In conclusion, PXM-188 at a weight ratio of 10.0% w/w was the best candidate in enhancing the solubility, stability and release of DIF.
PubMed: 32679660
DOI: 10.3390/polym12071564 -
Journal of Medicinal Chemistry Aug 2020Although nonsteroidal anti-inflammatory drugs (NSAIDs) target primarily cyclooxygenase enzymes, a subset of NSAIDs containing carboxylate groups also has been reported...
Although nonsteroidal anti-inflammatory drugs (NSAIDs) target primarily cyclooxygenase enzymes, a subset of NSAIDs containing carboxylate groups also has been reported to competitively inhibit dihydrofolate reductase (DHFR). In this study, we have characterized NSAID interactions with human DHFR based on kinetic, NMR, and X-ray crystallographic methods. The NSAIDs target a region of the folate binding site that interacts with the -aminobenzoyl-l-glutamate (pABG) moiety of folate and inhibit cooperatively with ligands that target the adjacent pteridine-recognition subsite. NSAIDs containing benzoate or salicylate groups were identified as having the highest potency. Among those tested, diflunisal, a salicylate derivative not previously identified to have anti-folate activity, was found to have a of 34 μM, well below peak plasma diflunisal levels reached at typical dosage levels. The potential of these drugs to interfere with the inflammatory process by multiple pathways introduces the possibility of further optimization to design dual-targeted analogs.
Topics: Anti-Inflammatory Agents, Non-Steroidal; Binding Sites; Crystallography, X-Ray; Drug Design; Folic Acid; Folic Acid Antagonists; Humans; Models, Molecular; Tetrahydrofolate Dehydrogenase
PubMed: 32658475
DOI: 10.1021/acs.jmedchem.0c00546 -
Orphanet Journal of Rare Diseases Jul 2020Patisiran, an RNA interference therapeutic, has demonstrated robust reduction of wild-type and mutant transthyretin protein and was able to improve polyneuropathy and...
BACKGROUND
Patisiran, an RNA interference therapeutic, has demonstrated robust reduction of wild-type and mutant transthyretin protein and was able to improve polyneuropathy and quality of life following 18 months of treatment in patients with hereditary transthyretin-mediated (hATTR) amyloidosis. In this 24-month Phase II open-label extension study, we evaluated the effects of patisiran treatment (0.3 mg/kg intravenously every 3 weeks) on safety, serum transthyretin levels, and clinical parameters. Efficacy assessments included modified Neuropathy Impairment Score +7 (mNIS+7) and multiple disease-relevant measures. Cardiac assessments were performed in a pre-specified cardiac subgroup.
RESULTS
Twenty-seven patients entered this study, including 12 (44%) with ambulation difficulties due to their neuropathy and 11 (41%) who met criteria for the cardiac subgroup. During treatment, the majority of adverse events were mild/moderate in severity; there were no drug-related adverse events leading to treatment discontinuation. The most common drug-related adverse events were flushing and infusion-related reactions (22% each). Patisiran resulted in rapid, robust (~ 82%), and sustained reduction of mean transthyretin levels over 24 months. A mean 6.95-point decrease (improvement) in mNIS+7 from baseline was observed at 24 months. Patisiran's impact on mNIS+7 was irrespective of concomitant tafamidis or diflunisal use, sex, or age. Clinical assessments of motor function, autonomic symptoms, disease stage, and quality of life remained stable over 24 months. No significant changes were observed for echocardiographic measures or cardiac biomarkers in the cardiac subgroup. Exploratory analyses demonstrated improvements in nerve-fiber density with corresponding reductions in amyloid burden observed in skin biopsies over 24 months.
CONCLUSIONS
Long-term treatment with patisiran had an acceptable safety profile and was associated with halting/improvement of polyneuropathy progression in patients with hATTR amyloidosis.
TRIAL REGISTRATION
The study was registered at ClinicalTrials.gov (identifier: NCT01961921 ) on October 14, 2013.
Topics: Amyloid Neuropathies, Familial; Humans; Prealbumin; Quality of Life; RNA, Small Interfering
PubMed: 32641071
DOI: 10.1186/s13023-020-01399-4 -
European Journal of Hospital Pharmacy :... Jul 2020To carry out a systematic review of the literature to analyse the efficacy and safety of treatments available or under investigation for amyloidosis due to mutations in...
OBJECTIVE
To carry out a systematic review of the literature to analyse the efficacy and safety of treatments available or under investigation for amyloidosis due to mutations in the transthyretin gene (ATTR).
METHODS
A bibliographic search was carried out in the following electronic databases up to September 2017: PubMed, Cochrane Library and EMBASE. The inclusion criteria were: efficacy and/or safety studies conducted in humans, studies that included treatments, including treatments in the research phase, and studies that included 10 or more patients.
RESULTS
A total of 21 articles were included; 16 were clinical trials, eight of them (50%) phase III trials, and five were observational studies. Of the total number of studies selected, 11 were on tafamidis, four on diflunisal, two on liver transplantation, two on patisiran and two on other therapeutic alternatives. Of the 11 studies related to the drug, the pivotal trial, the results of its two extension studies and an additional post hoc analysis were selected. In addition, two phase III trials were included in specific populations, two phase II studies, one safety study and two observational studies. Regarding the four included studies related to the drug, one was the pivotal trial that gave the indication to diflunisal, another a safety summary of the pivotal trial, and the other two trials were carried out in specific populations, one in a Japanese population and another phase I trial in cardiac amyloidosis in the USA. As far as other alternatives are concerned, of the six studies included in this section, two were related to liver transplantation, two to patisiran and two to different therapeutic alternatives.
CONCLUSIONS
Sufficient evidence has not been found that demonstrates superiority among the available oral alternatives, diflunisal or tafamidis, in the treatment of ATTR. Direct comparisons between both drugs and pharmacoeconomic studies would be necessary to select the most efficient treatment.
Topics: Amyloid Neuropathies, Familial; Benzoxazoles; Diflunisal; Humans; Liver Transplantation; RNA, Small Interfering
PubMed: 32587078
DOI: 10.1136/ejhpharm-2018-001823